Apparatus and method for detecting foreign objects in wireless power transmission system

ABSTRACT

Aspects of the present invention relate to an apparatus and method for detecting foreign objects in a wireless power transmission system. This specification provides a wireless power reception apparatus for detecting foreign objects, including a power measurement unit for generating required power information indicative of required power for the wireless power reception apparatus, sending the required power information to a wireless power transmission apparatus, and measuring power induced from the wireless power transmission apparatus and a secondary coil for receiving the power induced from the wireless power transmission apparatus. In accordance with the present invention, foreign objects intervened between the wireless power transmission apparatus and the wireless power reception apparatus are recognized, and a user removes the foreign objects. Accordingly, damage to a device attributable to foreign objects can be prevented.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/939,035, filed Jul. 10, 2013, which claims thebenefit of Korean Application No. 10-2012-0075276, filed Jul. 10, 2012,in the Korean Intellectual Property Office. All disclosures of thedocument named above are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Aspects of the present invention relate to the transmission of wirelesspower and, more particularly, to an apparatus and method for detectingforeign objects in a wireless power transmission system.

2. Description of the Related Art

In general, a battery pack functions to receive electric power(electrical energy) from an external charger and supply a power sourcefor driving a portable terminal (e.g., a mobile phone or a PDA) in acharging state. The battery pack includes a battery cell for chargingthe electrical energy, a circuit for charging or discharging the batterycell (i.e., supply the electrical energy to the portable terminal), etc.

An electrical coupling method for coupling the battery pack and thecharger for charging the battery pack used in this portable terminalwith the electrical energy source includes a terminal supply method forreceiving a commercial power source, converting the commercial powersource into voltage and current corresponding to the battery pack, andsupplying electrical energy to the battery pack through the terminal ofthe battery pack.

However, the terminal supply method has problems, such as an instantdischarge phenomenon due to a potential difference between terminals,damage and the occurrence of a fire due to foreign objects, naturaldischarge, and a reduction in the lifespan and performance of a batterypack.

In order to solve the problems, contactless type charging systems andcontrol methods using a wireless power transmission method are beingrecently proposed.

The contactless type charging system includes a contactless powertransmission apparatus for supplying electrical energy according to awireless power transmission method, a contactless power receptionapparatus for receiving the electrical energy from the contactless powertransmission apparatus, and charging a battery cell with the electricalenergy, etc.

Meanwhile, in the contactless type charging system, the contactlesspower reception apparatus is charged in the state in which it is placedin the contactless power transmission apparatus owing to thecharacteristics of the contactless method.

Here, if foreign objects, such as metal, are placed in the contactlesspower transmission apparatus, the transmission of the wireless power isnot smoothly performed due to the foreign objects and there is a problemin that a product is damaged due to an overload.

SUMMARY OF THE INVENTION

An object of the present invention provides an apparatus and method fordetecting foreign objects in a wireless power transmission system.

In accordance with an aspect of the present invention, there is provideda wireless power reception apparatus for detecting foreign objects. Theapparatus includes a secondary coil magnetically or resonantly coupledwith a primary coil included in a wireless power transmission apparatusand configured to receive wireless power and a power measurement unitconfigured to generate required power information indicative of a powerrequired by the wireless power reception apparatus, send the requiredpower information to the wireless power transmission apparatus, andmeasure the received wireless power.

The power measurement unit may configure a reception power measurementresult obtained by comparing the required power with the measuredwireless power and send the reception power measurement result to thewireless power transmission apparatus.

In accordance with another aspect of the present invention, there isprovided a wireless power reception apparatus for detecting foreignobjects. The apparatus includes a secondary coil coupled with a primarycoil included in a wireless power transmission apparatus and configuredto receive wireless power and a power measurement unit configured togenerate required power information indicative of required powernecessary for wireless charging, receive a generated power measurementreport indicative of wireless power generated from the wireless powertransmission apparatus from the wireless power transmission apparatus,configure a reception power measurement result obtained by comparing therequired power with the generated wireless power and analyzing a resultof the comparison, and send the required power information and thereception power measurement result to the wireless power transmissionapparatus.

In accordance with yet another aspect of the present invention, there isprovided a wireless power reception method of a wireless power receptionapparatus detecting foreign objects. The method includes generatingrequired power information indicative of required power for wirelesscharging, sending the required power information to a wireless powertransmission apparatus, receiving wireless power using a secondary coilcoupled with a primary coil included in the wireless power transmissionapparatus, measuring the received wireless power, configuring areception power measurement result obtained by comparing the requiredpower with the measured wireless power and analyzing a result of thecomparison, and sending the reception power measurement result to thewireless power transmission apparatus.

In accordance with yet another aspect of the present invention, there isprovided a wireless power transmission apparatus for detecting foreignobjects. The apparatus includes a control unit configured to receiverequired power information, indicative of required power necessary tocharge a wireless power reception apparatus from the wireless powerreception apparatus, generate a control signal for providing therequired power, and send the control signal to an electricity drivingunit, the electricity driving unit configured to apply an electricitydriving signal to a primary coil in response to the control signal, anda primary coil coupled with the electricity driving unit, coupled with asecondary coil included in the wireless power reception apparatus, andconfigured to send wireless power.

The control unit may receive a reception power measurement result,obtained by comparing wireless power measured by the wireless powerreception apparatus with the required power, from the wireless powerreception apparatus.

In accordance with yet another aspect of the present invention, there isprovided a wireless power transmission apparatus for detecting foreignobjects. The apparatus includes a control unit configured to receiverequired power information indicative of required power necessary tocharge a wireless power reception apparatus from the wireless powerreception apparatus, generate a control signal for providing therequired power, and send the control signal to an electricity drivingunit, the electricity driving unit configured to apply an electricitydriving signal to a primary coil in response to the control signal, aprimary coil coupled with the electricity driving unit, coupled with asecondary coil included in the wireless power reception apparatus, andconfigured to send wireless power, and a power measurement unitconfigured to measure wireless power generated from the primary coil.

The control unit may configure a generated power measurement reportindicative of the generated wireless power, send the generated powermeasurement report to the wireless power reception apparatus, andreceive a reception power measurement result, obtained by comparing thegenerated wireless power with the required power and analyzing a resultof the comparison, from the wireless power reception apparatus.

In accordance with yet another aspect of the present invention, there isprovided a wireless power transmission method of a wireless powertransmission apparatus detecting foreign objects. The method includesreceiving required power information indicative of required powernecessary to charge a wireless power reception apparatus from thewireless power reception apparatus, generating a control signal forproviding the required power and applying an electricity driving signalto a primary coil included in the wireless power transmission apparatus,sending wireless power, generated from the primary coil in response tothe electricity driving signal, to the wireless power receptionapparatus including a secondary coil coupled with the primary coil, andreceiving a reception power measurement result, obtained by comparingwireless power measured by the wireless power reception apparatus withthe required power and analyzing a result of the comparison, from thewireless power reception apparatus.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings, ofwhich:

FIG. 1 illustrates the elements of a wireless power transmission systemin accordance with an example of the present invention;

FIG. 2 illustrates an example of a method by which a wireless powerreception apparatus using the present invention detects foreign objects;

FIG. 3 illustrates an example of a method by which a wireless powertransmission apparatus using the present invention detects foreignobjects;

FIG. 4 illustrates another example of a method by which the wirelesspower transmission apparatus using the present invention detects foreignobjects;

FIG. 5 illustrates the elements of a wireless power transmission systemin accordance with another example of the present invention;

FIG. 6 illustrates the elements of a wireless power transmission systemin accordance with yet another example of the present invention;

FIG. 7 illustrates another example of a method by which a wireless powerreception apparatus using the present invention detects foreign objects;

FIG. 8 illustrates another example of a method by which a wireless powertransmission apparatus using the present invention detects foreignobjects; and

FIG. 9 is a flowchart illustrating the operation of the wireless powertransmission apparatus and the wireless power reception apparatus usingthe present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures.

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings so that they can bereadily implemented by those skilled in the art. A term ‘wireless power’used herein means energy having a specific form which is related to anelectric field, a magnetic field, or an electromagnetic fieldtransmitted from a transmitter to a receiver without using physicalelectromagnetic conductors. The wireless power may also be called apower signal and may mean an oscillating magnetic flux enclosed by aprimary coil and a secondary coil. For example, the conversion of powerin a system in order to wirelessly charge a device, such as a mobilephone, a cordless telephone, iPod®, an MP3® player, and a headset, isdescribed herein. In general, a basic transfer principle of wirelessenergy includes, for example, both a magnetic induction coupling methodand a magnetic resonance coupling (i.e., resonant induction) methodusing frequencies less than 30 MHz. However, various types offrequencies including frequencies in which a license-free operation inrelatively high radiation levels, for example, less than 135 kHz (LF) or13.56 MHz (HF) is permitted may be used.

FIG. 1 illustrates the elements of a wireless power transmission systemin accordance with an example of the present invention.

Referring to FIG. 1, the wireless power transmission system 1 includes awireless power transmission apparatus 10 and at least one wireless powerreception apparatus 30. The wireless power transmission apparatus 10includes a primary coil 12 and an electricity driving unit 14 coupledwith the primary coil 12 and configured to supply electricity drivingsignals to the primary coil 12 in order to generate an electromagneticfield. A control unit 16 is coupled with the electricity driving unit14. The control unit 16 generates a control signal 106 that controls anAC signal necessary when the primary coil 12 generates an inductivemagnetic field.

The wireless power transmission apparatus 10 can have a specific andproper form, and an exemplary form of the wireless power transmissionapparatus 10 is a platform having a power transmission surface. Awireless power reception apparatus 30 can be placed on or near theplatform.

The wireless power reception apparatus 30 can be separate from thewireless power transmission apparatus 10. The wireless power receptionapparatus 30 includes a secondary coil 32 coupled with anelectromagnetic field generated from the wireless power transmissionapparatus 10 when the wireless power reception apparatus 30 is placednear the wireless power transmission apparatus 10. In this method,electric power can be transmitted from the wireless power transmissionapparatus 10 to the wireless power reception apparatus 30 without adirect electrical contact. At this time, it is said that the primarycoil 12 and the secondary coil 32 have been mutually subjected tomagnetic induction coupling or resonant induction coupling.

The primary coil 12 and the secondary coil 32 can have specific andproper forms. Each of the primary coil 12 and the secondary coil 32 canbe a copper wire on which high permeable magnetic materials, such asferrite or amorphous metal, are surrounded. The secondary coil 32 mayhave a single core form or a dual coil form. Or, the secondary coil 32may include two or more coils.

In general, the wireless power reception apparatus 30 is coupled with anexternal load (not shown) (here, the external load is also called theactual load of the wireless power reception apparatus) and configured tosupply wireless power, received from the wireless power transmissionapparatus 10, to the external load. The wireless power receptionapparatus 30 can be delivered to an object requiring electric power,such as a portable electrical or electronic device, a rechargeablebattery, or a cell.

The wireless power reception apparatus 30 of the wireless powertransmission system 1 of FIG. 1 further includes a power measurementunit 31 coupled with the secondary coil 32.

The power measurement unit 31 generates required power information 33indicative of power required or requested by the wireless powerreception apparatus 30 and sends the required power information 33 tothe control unit 16. The required power information 33 is controlinformation for controlling wireless power to be supplied to thewireless power reception apparatus 30. The wireless power transmissionsystem 1 of FIG. 1 supports a unidirectional communication method bywhich control information is transmitted along a path from the wirelesspower reception apparatus 30 to the wireless power transmissionapparatus 10.

For example, the required power information 33 can numerically indicatethe amount of power required by the wireless power reception apparatus30. For example, if the wireless power reception apparatus 30 needselectric power of 10 W, the power measurement unit 31 can generate therequired power information 33 indicative of 10 W.

The control unit 16 checks the required power information 33 andgenerates the control signal 106 so that electric power indicated by therequired power information 33 is generated. For example, when therequired power information 33 indicates 10 W, the control unit 16generates the control signal 106 so that electric power of 10 W istransmitted. The electricity driving unit 14 receives the control signal106 and converts the received control signal 106 into an AC signal inthe primary coil 12 in order to generate an induction or resonantmagnetic field near the primary coil 12.

The power measurement unit 31 measures wireless power (or receivedwireless power) that is transferred from the primary coil 12 to thesecondary coil 32 in response to the AC signal. The wireless powermeasured by the power measurement unit 31 can be calculated based on adifference between wireless power, transferred from the primary coil 12to the secondary coil 32, and other losses due to foreign objects, suchas a parasitic load near the wireless power transmission system 1.

For example, it is assumed that wireless power of 10 W is generated fromthe primary coil 12 in response to the required power information 33 andthen transferred to the secondary coil 32 and power of 2 W is lost dueto foreign objects. Here, power actually transferred to the secondarycoil 32 (i.e., power actually received by the secondary coil 32) is 8 W.The power actually received by the secondary coil 32 is called receivedpower, and the received power is the total amount of power dissipatedwithin the wireless power reception apparatus 30 due to a magnetic fieldgenerated from the wireless power transmission apparatus.

The power measurement unit 31 sends or provides a reception powermeasurement result 34, reporting the results of measurement powerobtained by comparing required power with measured (or actuallyreceived) power and analyzing the comparison result, to the control unit16.

In an embodiment, the power measurement unit 31 can indicate adifference between required power and measured power as the receptionpower measurement result 34. In this case, the reception powermeasurement result 34 indicates 2 W.

In another embodiment, the power measurement unit 31 can indicate ameasured power value itself as the reception power measurement result34. In this case, the reception power measurement result 34 indicates 8W.

In yet another embodiment, the power measurement unit 31 can indicate aflag form (0 or 1), indicating whether there is a difference betweenrequired power and measured power or not, as the reception powermeasurement result 34. For example, if there is no difference betweenthe required power and the measured power, a flag is set to 1 (i.e.,flag=1). If there is a difference between the required power and themeasured power, a flag is set to 0 (i.e., flag=0), and the vice versa.In the above example, the reception power measurement result 34indicates 1.

In yet another embodiment, the power measurement unit 31 can determinewhether a difference between required power and measured power isgreater than or equal to or smaller than a threshold value and indicatea result of the determination as the reception power measurement result34. For example, if a difference between the required power and themeasured power is greater than the threshold value, the reception powermeasurement result 34 can be set to 1. If a difference between therequired power and the measured power is smaller than or equal to thethreshold value, the reception power measurement result 34 can be set to0. In the above example, if the threshold value is 1 W, the receptionpower measurement result 34 indicates 1 because lost power 2 W isgreater than 1 W. If a difference between the required power and themeasured power is greater than the threshold value, the reception powermeasurement result 34 (=1) has the same meaning as a Foreign ObjectDetection (FOD) declaration (described below) because it means thatforeign objects have been detected. For example, if the reception powermeasurement result 34 continues to be 1 without change for a specifictime, the wireless power transmission apparatus 10 can stop or suspendthe transmission of wireless power because it means that foreign objectscontinue to be present.

In yet another embodiment, if there is a difference between requiredpower and measured power, this has the same meaning as the FODdeclaration. In this case, the power measurement unit 31 can provide thecontrol unit 16 with the reception power measurement result 34indicative of the FOD declaration. If there is no difference betweenrequired power and measured power, the power measurement unit 31 may notprovide any signal to the control unit 16.

The control unit 16 receives the reception power measurement result 34.If it is determined that a significant parasitic load is present nearthe wireless power transmission apparatus 10 based on the receptionpower measurement result 34, the control unit 16 can enter a suspendingmode in which the driving of the primary coil 12 is decreased or stoppedso that the generation of the parasitic load is prevented. Accordingly,the supply of inefficient induction power can be limited or stopped.That is, the wireless power transmission apparatus 10 takes an actionagainst the detection of foreign objects. Or, the power measurement unit31 can enter a suspending mode in which the driving of the primary coil12 is decreased or stopped in order to prevent the generation of theparasitic load. That is, the wireless power reception apparatus 30 takesan action against the detection of foreign objects.

As described above, the present invention provides unidirectional powercontrol technology in which the wireless power reception apparatus 30sends a signal to the wireless power transmission apparatus 10 and theadditional power measurement unit 31 also measures power transmitted bythe wireless power transmission apparatus 10, compares the measuredpower with required power, and provides a result of the comparison tothe wireless power transmission apparatus 10.

FIG. 2 illustrates an example of a method by which the wireless powerreception apparatus 30 using the present invention detects foreignobjects.

Referring to FIG. 2, the wireless power reception apparatus 30 generatesthe required power information indicative of power requested by thewireless power reception apparatus 30 at step S200.

The wireless power reception apparatus 30 sends the required powerinformation to the wireless power transmission apparatus 10 at stepS205. When the primary coil 12 of the wireless power transmissionapparatus 10 generates the required power in response to the requiredpower information, the wireless power reception apparatus 30 receiveswireless power based on magnetic induction or magnetic resonance fromthe wireless power transmission apparatus 10 using the secondary coil 32at step S210.

The wireless power reception apparatus 30 measures wireless powerreceived in response to the required power information at step S215.Here, the measured power can be calculated based on a difference betweeninitial wireless power (or the required power), transferred from thewireless power transmission apparatus 10 to the wireless power receptionapparatus 30, and other losses due to foreign objects, such as a nearbyparasitic load.

The wireless power reception apparatus 30 provides the wireless powertransmission apparatus 10 with a reception power measurement result thatreports a result of comparison and analysis for the required power andthe measured power at step S215.

In an embodiment, the wireless power reception apparatus 30 can indicatea difference between the required power and the measured power as thereception power measurement result 34.

In another embodiment, the wireless power reception apparatus 30 canindicate the measured power value itself as the reception powermeasurement result 34.

In yet another embodiment, the wireless power reception apparatus 30 canindicate a flag form (0 or 1), indicating whether or not there is adifference between the required power and the measured power, as thereception power measurement result.

In yet another embodiment, the wireless power reception apparatus 30 candetermine whether a difference between the required power and themeasured power is greater than or equal to or smaller than a thresholdvalue and indicate a result of the determination as the reception powermeasurement result 34.

In yet another embodiment, if there is a difference between the requiredpower and the measured power, the wireless power reception apparatus 30can provide the wireless power transmission apparatus 10 with thereception power measurement result 34 indicating the difference. Ifthere is no difference between the required power and the measuredpower, the wireless power reception apparatus 30 may not provide thereception power measurement result 34 to the wireless power transmissionapparatus 10. In this case, the step S220 may not occur.

In yet another embodiment, the wireless power reception apparatus 30 candetermine whether the measured power is greater than or smaller than therequired power and indicate a result of the determination as thereception power measurement result 34. For example, the reception powermeasurement result can be indicated by ‘high’ or ‘low’. Here, ‘high’indicates that the measured power is greater than the required power,and ‘low’ indicates that the measured power is smaller than the requiredpower. Or, the reception power measurement result may be indicated byone of three states, including ‘high’, ‘low’, and ‘equal’.

FIG. 3 illustrates an example of a method by which the wireless powertransmission apparatus 10 using the present invention detects foreignobjects.

Referring to FIG. 3, the wireless power transmission apparatus 10receives the required power information 33 from the wireless powerreception apparatus 30 at step S300.

The wireless power transmission apparatus 10 sends wireless power to thewireless power reception apparatus 30 in accordance with a magneticinduction or magnetic resonance method in response to required powerindicated by the required power information 33 at step S305.

The wireless power transmission apparatus 10 receives the receptionpower measurement result 34, reporting an actual measurement result ofthe wireless power transmitted in response to the required power by thewireless power reception apparatus 30, from the wireless power receptionapparatus 30 at step S310.

If it is determined that foreign objects have been detected as a resultof analyzing the reception power measurement result 34, the wirelesspower transmission apparatus 10 enters the suspending mode in which thedriving of the primary coil 12 is decreased or stopped. Accordingly, thegeneration of heat from a parasitic load can be prevented, and thesupply of inefficient induction power can be limited or stopped.

FIG. 4 illustrates another example of a method by which the wirelesspower transmission apparatus 10 using the present invention detectsforeign objects.

Referring to FIG. 4, the steps S400 to S410 are the same as therespective steps S300 to S310 of FIG. 3, and thus a detailed descriptionthereof is omitted. Meanwhile, the step S410 can be limited by thefollowing various embodiments.

For example, in an embodiment in which the reception power measurementresult indicates whether the measured power is greater than (‘high’) orsmaller than (‘low’) the required power, the wireless power transmissionapparatus 10 determines whether or not the reception power measurementresult 34 indicating ‘low’ or ‘high’ has been received N timesidentically and continuously at step S415. Here, N indicates the numberof times of continuous reception of ‘low’ or ‘high’ that is necessaryfor the wireless power transmission apparatus 10 to stop thetransmission of wireless power, and N can be 2 (i.e., N=2). For example,if the reception power measurement result indicating ‘low’ has beencontinuously received twice, the wireless power transmission apparatus10 can stop the transmission of the wireless power as a measure againstthe detection of foreign objects at step S420. In contrast, if thereception power measurement result indicating ‘high’ has beencontinuously received twice, the wireless power transmission apparatus10 can stop the transmission of the wireless power as a measure againstthe detection of foreign objects at step S420.

In contrast, if the reception power measurement result indicating ‘low’or ‘high’ has been continuously received less than two times, thewireless power transmission apparatus 10 sends the wireless power to thewireless power reception apparatus 30 again at step S405. For example,if the reception power measurement result previously indicating ‘low’was received, but the reception power measurement result now indicating‘high’ is received, the wireless power transmission apparatus 10 doesnot stop the transmission of the wireless power because the samereception power measurement result does not continue to be received.

For another example, in an embodiment in which the reception powermeasurement result 34 indicates that there is a difference between therequired power and the measured power, if the wireless powertransmission apparatus 10 continues to receive the reception powermeasurement result indicative of ‘present difference’ N times, thewireless power transmission apparatus 10 can stop the transmission ofthe wireless power as a measure against the detection of foreign objectsat step S420.

For yet another example, in an embodiment in which the reception powermeasurement result 34 indicates that a difference between the requiredpower and the measured power is greater than or equal to or smaller thanthe threshold value, if the wireless power transmission apparatus 10continues to receive the reception power measurement result 34indicative of ‘great’ or ‘small’ N times, the wireless powertransmission apparatus 10 can stop the transmission of the wirelesspower as a measure against the detection of foreign objects at stepS420.

FIG. 5 illustrates the elements of a wireless power transmission systemin accordance with another example of the present invention.

Referring to FIG. 5, the wireless power transmission system 4 includes awireless power transmission apparatus 40 and at least one wireless powerreception apparatus 50. The wireless power transmission apparatus 40includes a primary coil 44 and an electricity driving unit 43 coupledwith the primary coil 44 and configured to supply electricity drivingsignals to the primary coil 44 in order to generate an electromagneticfield. A control unit 42 is coupled with the electricity driving unit43. The control unit 42 generates a control signal 45. The electricitydriving unit 43 receives the control signal 45 and converts the receivedcontrol signal 45 into an AC signal in the primary coil 44 in order togenerate an induction or resonance magnetic field near the primary coil44.

The wireless power transmission apparatus 40 can have a specific andproper form, and an exemplary form of the wireless power transmissionapparatus 40 is a platform having a power transmission surface. Thewireless power reception apparatus 50 can be placed on or near theplatform.

The wireless power reception apparatus 50 can be separate from thewireless power transmission apparatus 40. The wireless power receptionapparatus 50 includes a secondary coil 52 coupled with anelectromagnetic field generated from the wireless power transmissionapparatus 40 when the wireless power reception apparatus 50 is placednear the wireless power transmission apparatus 40. In this method,electric power can be transmitted from the wireless power transmissionapparatus 40 to the wireless power reception apparatus 50 without adirect electrical contact.

The primary coil 44 and the secondary coil 52 can have specific andproper forms. Each of the primary coil 44 and the secondary coil 52 canbe a copper wire on which high permeable magnetic materials, such asferrite or amorphous metal, are surrounded. The secondary coil 52 mayhave a single core form or a dual coil form. Or, the secondary coil 52may include two or more coils.

The wireless power reception apparatus 50 of the wireless powertransmission system 4 of FIG. 5 further includes a power measurementunit 51 coupled with the secondary coil 52.

The power measurement unit 51 generates required power information 53requested by the wireless power reception apparatus 50 and sends therequired power information 53 to the control unit 42. The required powerinformation 53 is control information for controlling power to besupplied to the wireless power reception apparatus 50.

For example, the required power information 53 can numerically indicatethe amount of power necessary for the wireless power reception apparatus50. For example, if the wireless power reception apparatus 50 requirespower of 10 W, the power measurement unit 51 can generate the requiredpower information 53 indicating 10 W.

The control unit 42 checks the required power information 53 andgenerates the control signal 45 so that power indicated by the requiredpower information 53 is generated. For example, when the required powerinformation 53 indicates 10 W, the control unit 42 generates the controlsignal 45 so that power of 10 W is transmitted. The electricity drivingunit 43 receives the control signal 45 and converts the received controlsignal 45 into an AC signal in the primary coil 44 in order to generatean induction or resonance magnetic field near the primary coil 44.

The wireless power transmission apparatus 40 further includes a primarypower measurement unit 41. The primary power measurement unit 41measures power generated from the primary coil 44 in response to the ACsignal. For example, the required power information 53 indicates 10 W,but actually generated power can be measured as 12 W. That is, in orderfor power, actually received by the wireless power reception apparatus50, to become 10 W in response to the indication of the required powerinformation 53, the primary coil 44 generates power of 12 W higher thanpower of 10 W. This is because power of 2 W has been lost due to foreignobjects attributable to a parasitic load near the wireless powertransmission system 4 in a process of the wireless power beingtransmitted from the primary coil 44 to the secondary coil 52.

The control unit 42 configures or generates a generated powermeasurement report 54 indicative of generation power measured by theprimary power measurement unit 41 and sends the generated powermeasurement report 54 to the power measurement unit 51. As describedabove, the wireless power transmission system 4 supports a bidirectionalcommunication method by which the control information 53 may betransmitted along a path from the wireless power reception apparatus 50to the wireless power transmission apparatus 40 and the pieces ofcontrol information 54 and 55 may be transmitted along a path from thewireless power transmission apparatus 40 to the wireless power receptionapparatus 50.

The power measurement unit 51 compares the required power with indicatedpower indicated by the generated power measurement report 54, analyzes adifference between the required power and the indicated power, anddetermines whether or not to make an FOD declaration based on a resultof the analysis.

In an embodiment, the power measurement unit 51 can determine whether adifference between the required power and the indicated power indicatedby the generated power measurement report 54 is greater than or equal toor smaller than a threshold value and indicate a result of thedetermination as a reception power measurement result 55. For example,if a difference between the required power and the indicated powerindicated by the generated power measurement report 54 is greater thanthe threshold value, the power measurement unit 51 can set the receptionpower measurement result 55 to 1. If a difference between the requiredpower and the indicated power indicated by the generated powermeasurement report 54 is smaller than or equal to the threshold value,the power measurement unit 51 can set the reception power measurementresult 55 to 0. Or, if a difference between the required power and theindicated power indicated by the generated power measurement report 54is greater than or equal to the threshold value, the power measurementunit 51 may set the reception power measurement result 55 to 1. If adifference between the required power and the indicated power indicatedby the generated power measurement report 54 is smaller than thethreshold value, the power measurement unit 51 may set the receptionpower measurement result 55 to 0. In this case, the subjects indicatedby the values 0 and 1 of the reception power measurement result 55 maybe changed.

For example, it is assumed that the threshold value is 1 W. If, as inthe above example, the indicated power indicated by the generated powermeasurement report 54 is 12 W and the required power is 10 W, adifference between the indicated power and the required power is 2 W,which is greater than the threshold value of 1 W. In this case, thereception power measurement result 55 indicates 1. If a differencebetween the required power and the indicated power indicated by thegenerated power measurement report 54 is greater than the thresholdvalue, it may mean that foreign objects have been detected.

An embodiment in which the power measurement unit 51 compares requiredpower with indicated power indicated by the generated power measurementreport 54 and analyzes a difference between the required power and theindicated power in order to make an FOD declaration has been describedabove. However, the power measurement unit 51 may compare power,actually received by the wireless power reception apparatus 50, withindicated power indicated by the generated power measurement report 54,analyze a difference between the actually received power and theindicated power, and make an FOD declaration based on a result of theanalysis. Here, a method for the comparison and analysis can beperformed like the method of comparing required power with indicatedpower indicated by the generated power measurement report 54 andanalyzing a difference between the required power and the indicatedpower.

If the wireless power transmission apparatus 40 sends wireless powergreater than required power (or power actually received by the wirelesspower reception apparatus 50) by a certain amount or higher or excessivewireless power owing to a loss due to foreign objects and thus thetransmitted wireless power satisfies the required power, an FODdeclaration is made in order to stop or suspend the transmission of thewireless power because wireless power efficiency can be deteriorated. Inthis sense, the reception power measurement result 55 (=1) may have thesame meaning as the FOD declaration. For example, if the reception powermeasurement result 55 (=1) continues to remain intact for a specifictime, it means that foreign objects continue to be present and thewireless power transmission apparatus 40 can stop or suspend thetransmission of wireless power.

The control unit 42 receives the reception power measurement result 55.If it is determined that a significant parasitic load is present nearthe wireless power transmission apparatus 40 based on the receptionpower measurement result 55, the control unit 42 can enter a suspendingmode in which the driving of the primary coil 44 is decreased or stoppedin order to prevent the generation of the parasitic load. Accordingly,the supply of inefficient induction power can be limited or stopped.That is, the wireless power transmission apparatus 40 takes an actionagainst the detection of foreign objects. Or, the power measurement unit51 may enter a suspending mode in which the driving of the primary coil44 is decreased or stopped in order to prevent the generation of heatfrom a parasitic load. That is, the wireless power reception apparatus50 takes an action against the detection of foreign objects.

As described above, the present invention provides bidirectional powercontrol technology in which the wireless power transmission apparatus 40sends wireless power to the wireless power reception apparatus 50 andthe control unit 42 also sends the generated power measurement report54, indicating power generated from or transmitted by the wireless powertransmission apparatus 40, to the wireless power reception apparatus 50.

FIG. 6 illustrates the elements of a wireless power transmission systemin accordance with yet another example of the present invention.

Referring to FIG. 6, a wireless power transmission apparatus 60 has thesame elements as the wireless power transmission apparatus 10 of FIG. 1.Meanwhile, a wireless power reception apparatus 70 has the same elementsas the wireless power reception apparatus 30 of FIG. 1 except that itfurther includes a measurement coil 71. The power measurement unit 31 iscoupled with the measurement coil 71. The measurement coil 71 may beprovided in such a way as to surround the outside of the secondary coil52 or may be provided within the secondary coil 52 in such a way as tosurround the inside of the secondary coil 52.

When a magnetic field or a current or voltage is primarily induced inthe secondary coil 52 by means of magnetic induction or magneticresonance between the primary coil 12 and the secondary coil 52, amagnetic field or a current or voltage is secondarily induced in themeasurement coil 71. The power measurement unit 31 can measure receivedwireless power using the magnetic field or a current or voltagesecondarily induced in the measurement coil 71.

FIG. 6 illustrates an example in which the measurement coil 71 isfurther added to the wireless power reception apparatus 30 of FIG. 1,but the measurement coil 71 may be likewise included in the wirelesspower reception apparatus 50 of FIG. 5.

FIG. 7 illustrates another example of a method by which the wirelesspower reception apparatus 50 using the present invention detects foreignobjects.

Referring to FIG. 7, the wireless power reception apparatus generatesthe required power information indicative of required power requested bythe wireless power reception apparatus at step S700.

The wireless power reception apparatus sends the required powerinformation to the wireless power transmission apparatus at step S705.When the wireless power transmission apparatus generates power inresponse to the required power information, the wireless power receptionapparatus receives wireless power based on magnetic induction orresonant induction from the wireless power transmission apparatus atstep S710.

The wireless power reception apparatus receives the generated powermeasurement report, which measures (or indicates) the power generatedfrom the wireless power transmission apparatus 40, from the wirelesspower transmission apparatus at step S715. Here, the power generatedfrom the wireless power transmission apparatus does not include a lossattributable to foreign objects and may differ from wireless poweractually received by the wireless power reception apparatus. Forexample, if a loss attributable to foreign objects is included in thepower generated from the wireless power transmission apparatus, thewireless power actually received by the wireless power receptionapparatus can be measured as being lower than the generated power.

The wireless power reception apparatus compares the required power (oractually received power) with the indicated power indicated by thegenerated power measurement report, analyzes a result of the comparison,and determines whether or not to make an FOD declaration based on aresult of the analysis at step S720.

In an embodiment, the wireless power reception apparatus can determinewhether a difference between the required power and the indicated powerindicated by the generated power measurement report is greater than orequal to or smaller than a threshold value and indicate a result of thedetermination as the reception power measurement result. For example, ifa difference between the required power and the indicated powerindicated by the generated power measurement report is greater than thethreshold value, the wireless power reception apparatus can set thereception power measurement result to 1. If a difference between therequired power and the indicated power indicated by the generated powermeasurement report is smaller than or equal to the threshold value, thewireless power reception apparatus can set the reception powermeasurement result to 0. Or, if a difference between the required powerand the indicated power indicated by the generated power measurementreport is greater than or equal to the threshold value, the wirelesspower reception apparatus may set the reception power measurement resultto 1. If a difference between the required power and the indicated powerindicated by the generated power measurement report is smaller than thethreshold value, the wireless power reception apparatus may set thereception power measurement result to 0. The subjects indicated by thevalues 0 and 1 of the reception power measurement result may be changed.

For example, it is assumed that the threshold value is 1 W. If, as inthe above example, the indicated power indicated by the generated powermeasurement report is 12 W and the required power is 10 W, a differencebetween the indicated power and the required power is 2 W, which isgreater than the threshold value of 1 W. In this case, the receptionpower measurement result indicates 1. If a difference between therequired power and the indicated power indicated by the generated powermeasurement report is greater than the threshold value, it may mean thatforeign objects have been detected.

The wireless power reception apparatus sends the reception powermeasurement result, reporting a result of the comparison and analysis,to the wireless power transmission apparatus at step S725.

FIG. 8 illustrates another example of a method by which the wirelesspower transmission apparatus using the present invention detects foreignobjects.

Referring to FIG. 8, the wireless power transmission apparatus receivesthe required power information from the wireless power receptionapparatus at step S800. The wireless power transmission apparatusgenerates wireless power based on magnetic induction in response torequired power indicated by the required power information. That is, thewireless power transmission apparatus checks the required powerinformation and generates the control signal so that the power indicatedby the required power information is induced. For example, when therequired power information indicates 10 W, the wireless powertransmission apparatus generates the control signal so that power of 10W is transmitted. The electricity driving unit receives the controlsignal and converts the received control signal into an AC signal in theprimary coil in order to generate an induction electromagnetic fieldnear the primary coil.

The wireless power transmission apparatus sends the generated wirelesspower to the wireless power reception apparatus at step S805.

At this time, the wireless power transmission apparatus measures powergenerated from the primary coil in response to the AC signal at stepS810. For example, the required power information indicates 10 W, butactually generated power may be measured as being 12 W. That is, inorder to transfer the power of 10 W to the wireless power receptionapparatus in response to the indication of the required powerinformation, the primary coil generates power of 12 W higher than thepower of 10 W. This is because power of 2 W has been lost due to foreignobjects attributable to a parasitic load in a process of the wirelesspower being transmitted from the primary coil to the secondary coil.

The wireless power transmission apparatus configures the generated powermeasurement report indicating the measured generation power and sendsthe configured generated power measurement report to the wireless powerreception apparatus at step S815. As described above, a bidirectionalcommunication method by which control information may be transmittedalong a path from the wireless power transmission apparatus to thewireless power reception apparatus and the control information may betransmitted along a path from the wireless power reception apparatus tothe wireless power transmission apparatus is made possible.

The wireless power transmission apparatus receives the reception powermeasurement result, that is, a result of comparison and analysis for therequired power (or actually received power) and the indicated powerindicated by the generated power measurement report, from the wirelesspower reception apparatus at step S820.

The reception power measurement result is information indicating whethera difference between the required power and the indicated powerindicated by the generated power measurement report is greater than orequal to or smaller than a threshold value. For example, if a differencebetween the required power and the indicated power indicated by thegenerated power measurement report is greater than the threshold value,the secondary reception power measurement result can be set to 1. If adifference between the required power and the indicated power indicatedby the generated power measurement report is smaller than or equal tothe threshold value, the reception power measurement result can be setto 0. In contrast, if a difference between the required power and theindicated power indicated by the generated power measurement report isgreater than or equal to the threshold value, the reception powermeasurement result may be set to 1. If a difference between the requiredpower and the indicated power indicated by the generated powermeasurement report is smaller than the threshold value, the receptionpower measurement result may be set to 0. The subjects indicated by thevalues 0 and 1 of the reception power measurement result may be changed.

For example, it is assumed that the threshold value is 1 W. If, as inthe above example, the indicated power indicated by the generated powermeasurement report is 12 W and the required power is 10 W, a differencebetween the indicated power and the required power is 2 W, which isgreater than the threshold value of 1 W. In this case, the receptionpower measurement result indicates 1. If a difference between therequired power and the indicated power indicated by the generated powermeasurement report is greater than the threshold value, it may mean thatforeign objects have been detected. Accordingly, the wireless powertransmission apparatus 40 can recognize this as an FOD declaration.

If it is determined that foreign objects have been detected as a resultof analyzing the reception power measurement result, the wireless powertransmission apparatus takes an action against the detection of theforeign objects at step S825. For example, the wireless powertransmission apparatus can enter a suspending mode in which the drivingof the primary coil 12 is decreased or stopped. Accordingly, thegeneration of heat from a parasitic load can be prevented, and thesupply of inefficient induction power can be limited or stopped.

FIG. 9 is a flowchart illustrating the operation of the wireless powertransmission apparatus and the wireless power reception apparatus usingthe present invention.

Referring to FIG. 9, the wireless power reception apparatus generatesthe required power information indicative of power requested by thewireless power reception apparatus at step S900.

The wireless power reception apparatus sends the required powerinformation to the wireless power transmission apparatus at step S905.When the primary coil of the wireless power transmission apparatusgenerates the required power in response to the required powerinformation, the secondary coil of the wireless power receptionapparatus receives wireless power based on magnetic induction ormagnetic resonance from the wireless power transmission apparatus atstep S910.

The wireless power reception apparatus measures wireless power receivedin response to the required power information at step S915. The powermeasurement unit may measure wireless power induced in the secondarycoil or may measure wireless power secondarily induced from thesecondary coil to the measurement coil. Here, the measured power can becalculated based on a difference between initial wireless power (orrequired power), transferred from the wireless power transmissionapparatus to the wireless power reception apparatus, and a lossattributable to foreign objects, such as a parasitic load that ispresent nearby.

The wireless power reception apparatus provides the wireless powertransmission apparatus with the reception power measurement result thatreports a result of comparison and analysis for the required power andthe measured power ate step S920.

In an embodiment, the reception power measurement result can be definedas a difference between the required power and the measured power.

In another embodiment, the reception power measurement result can bedefined as the measured power itself.

In yet another embodiment, the reception power measurement result may bedefined in the form of a flag (0 or 1) indicating whether or not thereis a difference between the required power and the measured power.

In further yet another embodiment, the reception power measurementresult can be defined as a result indicating whether a differencebetween the required power and the measured power is greater than orequal to or smaller than a threshold value.

In further yet another embodiment, the reception power measurementresult can be defined as information that is transmitted to the wirelesspower transmission apparatus only when there is a difference between therequired power and the measured power. That is, if there is nodifference between the required power and the measured power, thereception power measurement result is not transmitted to the wirelesspower transmission apparatus. In this case, the step S920 may beomitted.

In further yet another embodiment, the reception power measurementresult can be defined as a result indicating whether the measured poweris greater than or smaller than the required power. For example, thereception power measurement result can be indicated by ‘high’ or ‘low’.Here, ‘high’ indicates that the measured power is greater than therequired power, and ‘low’ indicates that the measured power is smallerthan the required power. Or, the reception power measurement result maybe indicated by any one of three states, including ‘high’, ‘low’, and‘equal’.

If it is determined that foreign objects have been detected as a resultof analyzing the reception power measurement result, the wireless powertransmission apparatus takes an action against the detection of theforeign objects at step S925. For example, the wireless powertransmission apparatus enters a suspending mode in which the driving ofthe primary coil is decreased or stopped. Accordingly, the generation ofheat from a parasitic load can be prevented, and the supply ofinefficient induction power can be limited or stopped.

The action taken by the wireless power transmission apparatus againstthe detection of foreign objects can include the following embodiments.For example, in an embodiment in which the reception power measurementresult indicates whether the measured power is greater than (‘high’) orsmaller than (‘low’) the required power, the wireless power transmissionapparatus determines whether or not the reception power measurementresult indicating ‘low’ or ‘high’ has been received identically andcontinuously N times. Here, N indicates the number of times ofcontinuous reception of ‘low’ or ‘high’ that is necessary for thewireless power transmission apparatus to stop the transmission ofwireless power, and N can be 2 (N=2). For example, if the receptionpower measurement result indicating ‘low’ has been continuously receivedtwice, the wireless power transmission apparatus can stop thetransmission of wireless power as a measure against the detection offoreign objects. In contrast, if the reception power measurement resultindicating ‘high’ has been continuously received twice, the wirelesspower transmission apparatus can stop the transmission of the wirelesspower as a measure against the detection of foreign objects.

In contrast, if the reception power measurement result indicating ‘low’or ‘high’ has been continuously received less than two times, thewireless power transmission apparatus determines that foreign objectshave not been detected and thus can send the wireless power to thewireless power reception apparatus again. For example, if the receptionpower measurement result previously indicating ‘low’ was received, butthe reception power measurement result now indicating ‘high’ isreceived, the wireless power transmission apparatus does not stop thetransmission of the wireless power because the same reception powermeasurement result does not continue to be received.

For another example, in an embodiment in which the reception powermeasurement result indicates that there is a difference between therequired power and the measured power, if the wireless powertransmission apparatus continues to receive the reception powermeasurement result indicative of ‘present difference’ N times, thewireless power transmission apparatus can stop the transmission of thewireless power as a measure against the detection of foreign objects.

For yet another example, in an embodiment in which the reception powermeasurement result indicates that a difference between the requiredpower and the measured power is greater than or equal to or smaller thanthe threshold value, if the wireless power transmission apparatuscontinues to receive the reception power measurement result indicativeof ‘great’ or ‘small’ N times, the wireless power transmission apparatuscan stop the transmission of the wireless power as a measure against thedetection of foreign objects.

All the functions can be executed by a processor, such as amicroprocessor, a controller, a microcontroller, or an ApplicationSpecific Integrated Circuit (ASIC) according to software or a programcode coded to perform the above functions. It can be said that thedesign, development, and implementation of the code is evident to thoseskilled in the art based on the description of the present invention.

In accordance with the present invention, foreign objects intervenedbetween the wireless power transmission apparatus and the wireless powerreception apparatus are recognized, and a user removes the foreignobjects. Accordingly, damage to a device attributable to foreign objectscan be prevented.

Although a few of the embodiments of the present invention have beenshown and described above, a person having ordinary skill in the artwill appreciate that the present invention can be modified, changed, andimplemented in various ways without departing from the principles,spirit and scope of the present invention. Accordingly, the presentinvention is not limited to the embodiments, and the present inventioncan be said to include all embodiments within the scope of the claimsbelow and their equivalents.

What is claimed is:
 1. A wireless power transmission method of awireless power transmission apparatus in a wireless power transmissionsystem comprising a power transmission path that is generated bymagnetic resonance coupling between a primary coil included in thewireless power transmission apparatus and a secondary coil included in awireless power reception apparatus, comprising: receiving first controlinformation using a communication path, wherein the first controlinformation is generated based on a desired power of the wireless powerreception apparatus; generating a wireless power based on the firstcontrol information, and transmitting the wireless power to the wirelesspower reception apparatus using the magnetic resonance coupling;receiving second control information using the communication path,wherein the second control information is generated based on a wirelesspower measured by the wireless power reception apparatus; andcontrolling the wireless power based on the first control informationand the second control information.
 2. The wireless power transmissionmethod of claim 1, wherein the first control information is anumerically indicated power value.
 3. The wireless power transmissionmethod of claim 1, wherein the controlling of the wireless powercomprises calculating a lost power based on the first controlinformation and the second control information, and determining that aforeign object is present when the lost power is greater than athreshold value.
 4. The wireless power transmission method of claim 3,wherein when the foreign object is determined to be present, thewireless power transmission apparatus is configured to execute a powersuspending mode.
 5. A wireless power reception method of a wirelesspower reception apparatus in a wireless power transmission systemcomprising a power transmission path that is generated by magneticresonance coupling between a primary coil included in a wireless powertransmission apparatus and a secondary coil included in the wirelesspower reception apparatus, comprising: generating first controlinformation based on a desired power of the wireless power receptionapparatus; transmitting the first control information to the wirelesspower transmission apparatus using a communication path; receiving awireless power generated based on the first control information usingthe magnetic resonance coupling; measuring an amount of the receivedwireless power; generating second control information based on themeasured wireless power; transmitting the second control information tothe wireless power transmission apparatus using the communication path;and receiving a wireless power controlled by the wireless powertransmission apparatus based on the first control information and thesecond control information.
 6. The wireless power reception method ofclaim 5, wherein the first control information is a numericallyindicated power value.
 7. The wireless power reception method of claim5, wherein the controlling, by the wireless power transmissionapparatus, the wireless power comprises calculating a lost power basedon the first control information and the second information, anddetermining that a foreign object is present when the lost power isgreater than a threshold value.
 8. The wireless power reception methodof claim 7, wherein when the foreign object is determined to be present,the wireless power transmission apparatus is configured to execute apower suspending mode.
 9. A wireless power transmission apparatus,comprising: a primary coil coupled with a secondary coil included in awireless power reception apparatus and configured to generate magneticresonance coupling with the secondary coil; and a control unitconfigured to receive first control information using a communicationpath, wherein the first control information is generated based on adesired power of the wireless power reception apparatus, wherein theprimary coil is configured to transmit a wireless power generated basedon the first control information to the secondary coil using themagnetic resonance coupling, and the control unit is configured toreceive second control information using the communication path, whereinthe second control information is generated based on a wireless powermeasured by the wireless power reception apparatus, and to control thewireless power based on the first control information and the secondcontrol information.
 10. The wireless power transmission apparatus ofclaim 9, wherein the first control information is a numericallyindicated power value.
 11. The wireless power transmission apparatus ofclaim 9, wherein the control unit is configured to calculate a lostpower based on the first control information and the second controlinformation, and to determine that a foreign object is present when thelost power is greater than a threshold value.
 12. The wireless powertransmission apparatus of claim 11, wherein when the foreign object isdetermined to be present, the wireless power transmission apparatus isconfigured to execute a power suspending mode.
 13. A wireless powerreception apparatus, comprising: a secondary coil coupled with a primarycoil included in a wireless power transmission apparatus and configuredto generate magnetic resonance coupling with the primary coil; and ameasurement unit configured to transmit first control information usinga communication method, wherein the first control information isgenerated based on a desired power of the wireless power receptionapparatus, wherein the secondary coil is configured to receive awireless power generated based on the first control information usingthe magnetic resonance coupling, and the measurement unit is configuredto measure an amount of the received wireless power, and to transmitsecond control information using the communication path, wherein thesecond control information is generated based on a wireless powermeasured by the wireless power reception apparatus, so that the wirelesspower is controlled by the wireless power transmission apparatus basedon the first control information and the second control information. 14.The wireless power reception apparatus of claim 13, wherein the firstcontrol information is a numerically indicated power value.
 15. Thewireless power reception apparatus of claim 13, wherein the wirelesspower transmission apparatus is configured to calculate a lost powerbased on the first control information and the second information, andto determine that a foreign object is present when the lost power isgreater than a threshold value.
 16. The wireless power receptionapparatus of claim 15, wherein when the foreign object is determined tobe present, the wireless power transmission apparatus is configured toexecute a power suspending mode.